weber 4.3 running rich, bogs when secondaries open

[benbob]

Ok, to start with: I have a 94 20ft boat with a vortec 4.3 LX with a weber 4bbl carb. its has an alpha one outdrive with these numbers on the prop: 3x15.5x13. The boat came with a prevortec engine, but had a rod haging out the side fo the block, so the previous owner put a vortec engine in it. He go a cast intake for the vortec heads. It had the opening for a qjet carb so I bought an edelbrock(part number 2696) adapter plate with 4 seperate holes to fit the weber. Previous owner said it never felt like it was running as it should, not enough power/RPM etc, but started/idled ok. We didn't touch a thing(before I put the adapter plate on) and took it out to a small lake to test it. It has been sitting for 4 years. The highest RPM we could ge out of it was 3,300 or so under a load. Would free rev to about 4500. The engine seemed to change sound at WOT under a load. Now I have the boat back at the shop and it looks like its just dumping way too much fuel in there, and it bogs when the secondaries open. This is when I put the adapter plate on. After installing the adapter plate, it wouldn't idle, and didn't like low RPMs. So then I bought a carb rebuild kit and went through the carb shooting carb cleaner through every port possible, installed the kit, and still same results.

Any suggestions on where to start??
I think today I'm going to pull the carb and take it to a well known guy here to have him check it out and see what he thinks about the qjet manifold and the adapter I'm using.

If I didn't include enough info for this, let me know and I'll get what is needed.


EDIT: oh yeah. I pulled a plug and it was black. not really any brown to be seen.

 

[z284u2try]

Re: weber 4.3 running rich, bogs when secondaries open

Sounds like it needs to be rejetted. What cfm is the carb?
My car falls on its face spraying nitrous when I forget to turn the bottle on and spray just fuel.
All plugs black?
Ever taken comprssion on the engine?

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

I only pulled one plug. I am unsure of the cm rating on this carb. I think I'v read on here that it's a 600 or 650. It's what came stock on the non vortec v6 in this boat. I have not checked compression yet.

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

Ok, I went out there again and got it warmed up a little more and the idle and low rpm issue are ok. The main concern is going to be the slow rev that bogs when the secondaries open.

I'll go uot and check compression in a little bit.

 

[z284u2try]

Re: weber 4.3 running rich, bogs when secondaries open

just going to throw this out there.
I think you check your high speed jetting.
I think you have the wrong prop on the boat if the pitch is 13.

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

I have no idea wha the prop is supposed to be. I will have to get another one anyway. This one got chewed up when we took it out. Right now, I have the boat out of water with muffs on it and am having the problem. It is highly unlikely that the carb has been into before me. The last owner(I have worked with him for 4 years) bought it from family that were the original owners. As far as he knows, it was never touched. I'm not rulling that out though.

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

compression is about 165 across the board.

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

Spark plugs are autolight 104s.

 

[180shabah]

Re: weber 4.3 running rich, bogs when secondaries open

Did you soak the carb and use compressed air, or just spray a little cleaner at it?

Also, what about a full/complete tune up?
Is the flame arrestor clean?

 

[Bondo]

Re: weber 4.3 running rich, bogs when secondaries open

Spark plugs are autolight 104s.

Ayuh,... It's a Chevy,....
It takes the AC Delco MR43T sparkplugs,..
Or, if it's in fact Vortec heads it's the AC Delco MR43LTS I believe....
Make Sure their Vortecs,+ not just the name Vortec on the valve covers,...
The Vortec sparkplugs are considerably Longer,+ can interfere with the Pistons in Non-Vortec applications......

EDIT: oh yeah. I pulled a plug and it was black. not really any brown to be seen.

Btw,.... That,.. Is a Carb Issue...

Those Weber carbs are an Exact copy of the Edlebrocks,...
Parts,+ whatnots are Cheap,+ Available through Edlebrock...
The Street/ Strip Kit is pretty much a Must Have for serious Tuning...
Also there's a Great write-up at the Edlebrock website on just How to Do It...

 

[180shabah]

Re: weber 4.3 running rich, bogs when secondaries open

can interfere with the Pistons in Non-Vortec applications......

I think it is pronounced - thunk.

Also, short plugs will in a vortec will run, but not well. Verify everything, you don't who did what before you got it.

 

[tricone]

Re: weber 4.3 running rich, bogs when secondaries open

I Have a very similar set up and i have 16+16 prop ... i can rarely get over
3800 rpm i know that i'm over propped and when i learned that.. i was content to stay off the 4 barrels i'm satisfied with the top end (about 32 mph.)
i think that you are just over propped....
the Q-jet is a spread bore carb the weber can be both as can the edlebrock,
i don't think you need that adapter as it is for a square bore carb

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

base timing at temp is 15 and advances to 25. Does this sound ok? 15 seems a little high at idle.

How to I determine if they are for sure vortec heads??

I did not soak the carb and use compressed air, just the small amount of pressure from the can of carb cleaner.

Iv' been doing this w/o the flame arrestor on it, so it's not a factor right now.

Now that it's hot outside, this thing idles and does GREAT at low RPMs. It will pop and shoot some smoke out of the carb as soon as the secondaries open.

thanks for all this help guys!!

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

It can't be a prop issue. Im not saying I don't need to change my prop though(I need to firgure out what prop I do need though since this one is chewed up). It's doing this out of the water.

Also, after doing some reading the autolite 104 is a vortec style plug.


I think my next steps will be to see about getting that base timing down to 10. Draining the fuel and putting fresh fuel in it. This gas is stinky bad. The engine ran the exact same with good fuel, but I just want fresh stuff in it.
I think I saw a thread that had number for jets somewhere. I'll see if I can tell what jets are in this carb. I'm not looking to get any serious tuning done here, just run like it's supposed to. But if that means getting a jet kit then I will do that.

 

[Bondo]

Re: weber 4.3 running rich, bogs when secondaries open

I think I saw a thread that had number for jets somewhere. I'll see if I can tell what jets are in this carb. I'm not looking to get any serious tuning done here, just run like it's supposed to. But if that means getting a jet kit then I will do that.

Ayuh,... That carb ran on a 4.3l Before,... That says the original Jets are just Fine...
You probably need a Real Carb Rebuild.... Or a Replacement Carb...

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

I guess that's what I get for buying a fake one. haha j/k

Where to I get a better rebuild kit? A kit directly from Edelbrock??

I don't have enough experiance with carbs to be confident with my rebuild. I didn't pull the jets out of the float bowl, nor did I measure the floats. They looked about parallel with theflat surface on the carb when holding the upper 1/2 upside down.

 

[Tail_Gunner]

Re: weber 4.3 running rich, bogs when secondaries open

I think it is pronounced - thunk.

Also, short plugs will in a vortec will run, but not well. Verify everything, you don't who did what before you got it.

Easy there shabah...I believe you were the one to tell me to stay away from TBI and carb a motor....aka jesss i thunk it would be a good ideer...

 

[Tail_Gunner]

Re: weber 4.3 running rich, bogs when secondaries open

It can't be a prop issue. Im not saying I don't need to change my prop though(I need to firgure out what prop I do need though since this one is chewed up). It's doing this out of the water.

Also, after doing some reading the autolite 104 is a vortec style plug.


I think my next steps will be to see about getting that base timing down to 10. Draining the fuel and putting fresh fuel in it. This gas is stinky bad. The engine ran the exact same with good fuel, but I just want fresh stuff in it.
I think I saw a thread that had number for jets somewhere. I'll see if I can tell what jets are in this carb. I'm not looking to get any serious tuning done here, just run like it's supposed to. But if that means getting a jet kit then I will do that.

Also, after doing some reading the autolite 104 is a vortec style plug.


Not even close autolite is a ford plug and AC delco is a gm plug and they do not mix.. yeah they will run with one leg broken..

 

[PitchFork]

Re: weber 4.3 running rich, bogs when secondaries open

I am having the same problem with my 4bbl Rochester and found that I purchased a carb online late last year and it had the wrong secondary rods and accelerator pump for my setup. Tonight when I was out on the lake I played with the pump and found that it only sprayed fuel through half throttle. I pulled a pump out of my old carb and it looked different. The cup is bigger on the old one. I pulled the top of the carb and put in the other pump and it sprayed fuel through the whole cycle of the throttle. I cannot wait to test it now but it is a little too dark. I will wait till Saturday.

 

[benbob]

Re: weber 4.3 running rich, bogs when secondaries open

Also, after doing some reading the autolite 104 is a vortec style plug.


Not even close autolite is a ford plug and AC delco is a gm plug and they do not mix.. yeah they will run with one leg broken..

This was not my choice of plug. What I'm saying is that changing the plug is no going fix myproblem. I read on some 4.3 vortec forums and a few people there use he autolite 104 without problems.

I just took a bunch of pills before going to the dentist to have m wisdom teeth pulled and I'm trying to finish this while I can still function. It's hittin me pretty hard. hah